Delivery of subunit influenza vaccine to skin with microneedles improves immunogenicity and long-lived protection.

Influenza infection represents a major socio-economic burden worldwide. Novel delivery methods can render influenza vaccination easier and more acceptable by the public, and importantly confer protection equal or superior to that induced by conventional systemic administration. An attractive target for vaccine delivery is the skin. Recent studies have demonstrated improved immune responses after transdermal delivery of inactivated influenza virus with microneedle patches. Here we show that immunization with a licensed influenza subunit vaccine coated on metal microneedles can activate both humoral and cellular arms of the immune response and confer improved long-term protection in the mouse model when compared to the conventional systemic route of delivery. These results demonstrate the promising potential of microneedle delivery of licensed influenza subunit vaccines, that could be beneficial in increasing vaccine coverage and protection and reducing influenza-related mortality worldwide.